Rectifier structure is commonly utilized for connecting a plurality of semiconductor diodes in parallel in order to obtain a high-current-handling capacity which cannot be obtained with a single diode. When the diodes are connected in this manner, they must be matched in characteristics to avoid imbalances in the amount of current conducted by the individual diodes. Imbalances of current flow can result in a diode carrying more than its proportionate share of the current which, in turn, can result in a thermal-runaway condition, that is, a condition in which the temperature and conductance of the diode increases thereby causing it to pass an even greater part of the current of the rectifier structure.
Once a thermal-runaway condition has been reached, the increase in temperature and current flow through the individual diode will eventually destroy that diode. In some circumstances, the destruction of an individual diode results in a short circuit in that particular diode and renders the entire rectifier inoperative.
One rectifier structure comprised of individual diodes is disclosed in U.S. Pat. No. 4,554,574 to Wright. A plate electrically interconnects the anodes and a current-regulating plate interconnects the cathodes. The current-regulating plate includes a central conduction area, a plurality of link areas, and a plurality of diode-contact areas. In the event of excessive current flow through a particular diode, the associated link area opens. A disadvantage of this structure is that it requires the replacement of the entire current-regulating plate once a link area opens.
The Wright structure further includes an insulated diode spacer having a plurality of holes for the diodes, an insulated ring against the current regulating plate links to keep the link areas in contact with the diodes, and a washer which forces the ring against the link areas.
Another disadvantage of the Wright structure is the need to carefully align the current-regulating plate such that its diode-contact areas are firmly connected to the diodes. Also, the diode spacer is not compressible.